Cogongrass

Domestic Programs Pest Evaluation. Arthur E. Miller, USDA-APHIS-PPQ, AERO, Raleigh, NC. March 27, 2003

Scientific name: Imperata cylindrica (L.) Beauv (Poaceae)

Physical description: Cogongrass is a perennial plant. It usually grows to 3 feet tall and looks similar to Johnsongrass. The leaves have an off-center and whitish midrib. Basal leaves may grow up to 3 feet long and 1/2 inch wide. The leaf margins rough and translucent.

The flowers (spikelets) are grouped into a large panicle with a fuzzy, plume-like structure which can float through the air. These hairy structures are shiny and give the panicle a cottony or silky appearance.

Origin and North American Distribution: Cogongrass (CG) is native to the Old World tropics and was introduced into AL, FL, and MS for forage and erosion control. Currently it is found in AL, FL, GA, LA, MS, SC, TX, and VA.

Quarantines: CG is a Federal Noxious Weed.

Dispersal: Seeds and rhizomes are spread along highways by mowers and other equipment. Some nurseries sell bloodgrass which may be stressed a wild type or return to wild type.

Control: Property managers and cooperators may use these strategies:

Cultural Control. Cultivation and burning do not help unless they are followed by a timely herbicide application.

Chemical Control. Several herbicides can be used on CG. PPQ Methods recommends a 2% glyphosate application for roadsides and fields. Centepede lawn may be treated with a selective herbicide such as sethoxydim. Late fall is an excellent time to begin to apply herbicides because plants are sending carbohydrates into roots and rhizomes for storage.

Biological Control. There are plants, insects, nematodes, and pathogens which hold CG in check in the Old World tropics, where it is native. There is no approved agent for release in the U.S.

Economic impact: CG ranks as the world's seventh worst weed and currently infests over 1250 million acres worldwide. It infests agricultural, forest, urban, and natural areas. The tall dead leaves are a roadside fire hazard. CG harms pine plantings because it is weedy and a fire hazard. CG has a negative impact on gross receipts from National Forest land relative to recreational user fees, timber sales, land use fees and mineral leases.

Environmental impact: It grows along road edges and in disturbed areas, but then invades and disrupts native plant communities. It is unpalatable as a forage and not suited for erosion control because of its agressive weedy nature. As herbivorous wildlife populations decrease, some predatory species are adversely effected.

Benefits of control: Agricultural, forest, urban and natural areas benefit can from control and prevention of further spread of this FNW.